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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2007 The Guava Authors<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * Licensed under the Apache License, Version 2.0 (the "License");<a name="line.4"></a>
<span class="sourceLineNo">005</span> * you may not use this file except in compliance with the License.<a name="line.5"></a>
<span class="sourceLineNo">006</span> * You may obtain a copy of the License at<a name="line.6"></a>
<span class="sourceLineNo">007</span> *<a name="line.7"></a>
<span class="sourceLineNo">008</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * Unless required by applicable law or agreed to in writing, software<a name="line.10"></a>
<span class="sourceLineNo">011</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.11"></a>
<span class="sourceLineNo">012</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * See the License for the specific language governing permissions and<a name="line.13"></a>
<span class="sourceLineNo">014</span> * limitations under the License.<a name="line.14"></a>
<span class="sourceLineNo">015</span> */<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>package com.google.common.collect;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import com.google.common.annotations.GwtCompatible;<a name="line.19"></a>
<span class="sourceLineNo">020</span>import com.google.common.annotations.GwtIncompatible;<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.lang.reflect.Array;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import java.util.Collection;<a name="line.23"></a>
<span class="sourceLineNo">024</span><a name="line.24"></a>
<span class="sourceLineNo">025</span>import javax.annotation.Nullable;<a name="line.25"></a>
<span class="sourceLineNo">026</span><a name="line.26"></a>
<span class="sourceLineNo">027</span>/**<a name="line.27"></a>
<span class="sourceLineNo">028</span> * Static utility methods pertaining to object arrays.<a name="line.28"></a>
<span class="sourceLineNo">029</span> *<a name="line.29"></a>
<span class="sourceLineNo">030</span> * @author Kevin Bourrillion<a name="line.30"></a>
<span class="sourceLineNo">031</span> * @since 2.0 (imported from Google Collections Library)<a name="line.31"></a>
<span class="sourceLineNo">032</span> */<a name="line.32"></a>
<span class="sourceLineNo">033</span>@GwtCompatible(emulated = true)<a name="line.33"></a>
<span class="sourceLineNo">034</span>public final class ObjectArrays {<a name="line.34"></a>
<span class="sourceLineNo">035</span>  static final Object[] EMPTY_ARRAY = new Object[0];<a name="line.35"></a>
<span class="sourceLineNo">036</span><a name="line.36"></a>
<span class="sourceLineNo">037</span>  private ObjectArrays() {}<a name="line.37"></a>
<span class="sourceLineNo">038</span><a name="line.38"></a>
<span class="sourceLineNo">039</span>  /**<a name="line.39"></a>
<span class="sourceLineNo">040</span>   * Returns a new array of the given length with the specified component type.<a name="line.40"></a>
<span class="sourceLineNo">041</span>   *<a name="line.41"></a>
<span class="sourceLineNo">042</span>   * @param type the component type<a name="line.42"></a>
<span class="sourceLineNo">043</span>   * @param length the length of the new array<a name="line.43"></a>
<span class="sourceLineNo">044</span>   */<a name="line.44"></a>
<span class="sourceLineNo">045</span>  @GwtIncompatible("Array.newInstance(Class, int)")<a name="line.45"></a>
<span class="sourceLineNo">046</span>  @SuppressWarnings("unchecked")<a name="line.46"></a>
<span class="sourceLineNo">047</span>  public static &lt;T&gt; T[] newArray(Class&lt;T&gt; type, int length) {<a name="line.47"></a>
<span class="sourceLineNo">048</span>    return (T[]) Array.newInstance(type, length);<a name="line.48"></a>
<span class="sourceLineNo">049</span>  }<a name="line.49"></a>
<span class="sourceLineNo">050</span><a name="line.50"></a>
<span class="sourceLineNo">051</span>  /**<a name="line.51"></a>
<span class="sourceLineNo">052</span>   * Returns a new array of the given length with the same type as a reference<a name="line.52"></a>
<span class="sourceLineNo">053</span>   * array.<a name="line.53"></a>
<span class="sourceLineNo">054</span>   *<a name="line.54"></a>
<span class="sourceLineNo">055</span>   * @param reference any array of the desired type<a name="line.55"></a>
<span class="sourceLineNo">056</span>   * @param length the length of the new array<a name="line.56"></a>
<span class="sourceLineNo">057</span>   */<a name="line.57"></a>
<span class="sourceLineNo">058</span>  public static &lt;T&gt; T[] newArray(T[] reference, int length) {<a name="line.58"></a>
<span class="sourceLineNo">059</span>    return Platform.newArray(reference, length);<a name="line.59"></a>
<span class="sourceLineNo">060</span>  }<a name="line.60"></a>
<span class="sourceLineNo">061</span><a name="line.61"></a>
<span class="sourceLineNo">062</span>  /**<a name="line.62"></a>
<span class="sourceLineNo">063</span>   * Returns a new array that contains the concatenated contents of two arrays.<a name="line.63"></a>
<span class="sourceLineNo">064</span>   *<a name="line.64"></a>
<span class="sourceLineNo">065</span>   * @param first the first array of elements to concatenate<a name="line.65"></a>
<span class="sourceLineNo">066</span>   * @param second the second array of elements to concatenate<a name="line.66"></a>
<span class="sourceLineNo">067</span>   * @param type the component type of the returned array<a name="line.67"></a>
<span class="sourceLineNo">068</span>   */<a name="line.68"></a>
<span class="sourceLineNo">069</span>  @GwtIncompatible("Array.newInstance(Class, int)")<a name="line.69"></a>
<span class="sourceLineNo">070</span>  public static &lt;T&gt; T[] concat(T[] first, T[] second, Class&lt;T&gt; type) {<a name="line.70"></a>
<span class="sourceLineNo">071</span>    T[] result = newArray(type, first.length + second.length);<a name="line.71"></a>
<span class="sourceLineNo">072</span>    System.arraycopy(first, 0, result, 0, first.length);<a name="line.72"></a>
<span class="sourceLineNo">073</span>    System.arraycopy(second, 0, result, first.length, second.length);<a name="line.73"></a>
<span class="sourceLineNo">074</span>    return result;<a name="line.74"></a>
<span class="sourceLineNo">075</span>  }<a name="line.75"></a>
<span class="sourceLineNo">076</span><a name="line.76"></a>
<span class="sourceLineNo">077</span>  /**<a name="line.77"></a>
<span class="sourceLineNo">078</span>   * Returns a new array that prepends {@code element} to {@code array}.<a name="line.78"></a>
<span class="sourceLineNo">079</span>   *<a name="line.79"></a>
<span class="sourceLineNo">080</span>   * @param element the element to prepend to the front of {@code array}<a name="line.80"></a>
<span class="sourceLineNo">081</span>   * @param array the array of elements to append<a name="line.81"></a>
<span class="sourceLineNo">082</span>   * @return an array whose size is one larger than {@code array}, with<a name="line.82"></a>
<span class="sourceLineNo">083</span>   *     {@code element} occupying the first position, and the<a name="line.83"></a>
<span class="sourceLineNo">084</span>   *     elements of {@code array} occupying the remaining elements.<a name="line.84"></a>
<span class="sourceLineNo">085</span>   */<a name="line.85"></a>
<span class="sourceLineNo">086</span>  public static &lt;T&gt; T[] concat(@Nullable T element, T[] array) {<a name="line.86"></a>
<span class="sourceLineNo">087</span>    T[] result = newArray(array, array.length + 1);<a name="line.87"></a>
<span class="sourceLineNo">088</span>    result[0] = element;<a name="line.88"></a>
<span class="sourceLineNo">089</span>    System.arraycopy(array, 0, result, 1, array.length);<a name="line.89"></a>
<span class="sourceLineNo">090</span>    return result;<a name="line.90"></a>
<span class="sourceLineNo">091</span>  }<a name="line.91"></a>
<span class="sourceLineNo">092</span><a name="line.92"></a>
<span class="sourceLineNo">093</span>  /**<a name="line.93"></a>
<span class="sourceLineNo">094</span>   * Returns a new array that appends {@code element} to {@code array}.<a name="line.94"></a>
<span class="sourceLineNo">095</span>   *<a name="line.95"></a>
<span class="sourceLineNo">096</span>   * @param array the array of elements to prepend<a name="line.96"></a>
<span class="sourceLineNo">097</span>   * @param element the element to append to the end<a name="line.97"></a>
<span class="sourceLineNo">098</span>   * @return an array whose size is one larger than {@code array}, with<a name="line.98"></a>
<span class="sourceLineNo">099</span>   *     the same contents as {@code array}, plus {@code element} occupying the<a name="line.99"></a>
<span class="sourceLineNo">100</span>   *     last position.<a name="line.100"></a>
<span class="sourceLineNo">101</span>   */<a name="line.101"></a>
<span class="sourceLineNo">102</span>  public static &lt;T&gt; T[] concat(T[] array, @Nullable T element) {<a name="line.102"></a>
<span class="sourceLineNo">103</span>    T[] result = arraysCopyOf(array, array.length + 1);<a name="line.103"></a>
<span class="sourceLineNo">104</span>    result[array.length] = element;<a name="line.104"></a>
<span class="sourceLineNo">105</span>    return result;<a name="line.105"></a>
<span class="sourceLineNo">106</span>  }<a name="line.106"></a>
<span class="sourceLineNo">107</span><a name="line.107"></a>
<span class="sourceLineNo">108</span>  /** GWT safe version of Arrays.copyOf. */<a name="line.108"></a>
<span class="sourceLineNo">109</span>  static &lt;T&gt; T[] arraysCopyOf(T[] original, int newLength) {<a name="line.109"></a>
<span class="sourceLineNo">110</span>    T[] copy = newArray(original, newLength);<a name="line.110"></a>
<span class="sourceLineNo">111</span>    System.arraycopy(<a name="line.111"></a>
<span class="sourceLineNo">112</span>        original, 0, copy, 0, Math.min(original.length, newLength));<a name="line.112"></a>
<span class="sourceLineNo">113</span>    return copy;<a name="line.113"></a>
<span class="sourceLineNo">114</span>  }<a name="line.114"></a>
<span class="sourceLineNo">115</span><a name="line.115"></a>
<span class="sourceLineNo">116</span>  /**<a name="line.116"></a>
<span class="sourceLineNo">117</span>   * Returns an array containing all of the elements in the specified<a name="line.117"></a>
<span class="sourceLineNo">118</span>   * collection; the runtime type of the returned array is that of the specified<a name="line.118"></a>
<span class="sourceLineNo">119</span>   * array. If the collection fits in the specified array, it is returned<a name="line.119"></a>
<span class="sourceLineNo">120</span>   * therein. Otherwise, a new array is allocated with the runtime type of the<a name="line.120"></a>
<span class="sourceLineNo">121</span>   * specified array and the size of the specified collection.<a name="line.121"></a>
<span class="sourceLineNo">122</span>   *<a name="line.122"></a>
<span class="sourceLineNo">123</span>   * &lt;p&gt;If the collection fits in the specified array with room to spare (i.e.,<a name="line.123"></a>
<span class="sourceLineNo">124</span>   * the array has more elements than the collection), the element in the array<a name="line.124"></a>
<span class="sourceLineNo">125</span>   * immediately following the end of the collection is set to {@code null}.<a name="line.125"></a>
<span class="sourceLineNo">126</span>   * This is useful in determining the length of the collection &lt;i&gt;only&lt;/i&gt; if<a name="line.126"></a>
<span class="sourceLineNo">127</span>   * the caller knows that the collection does not contain any null elements.<a name="line.127"></a>
<span class="sourceLineNo">128</span>   *<a name="line.128"></a>
<span class="sourceLineNo">129</span>   * &lt;p&gt;This method returns the elements in the order they are returned by the<a name="line.129"></a>
<span class="sourceLineNo">130</span>   * collection's iterator.<a name="line.130"></a>
<span class="sourceLineNo">131</span>   *<a name="line.131"></a>
<span class="sourceLineNo">132</span>   * &lt;p&gt;TODO(kevinb): support concurrently modified collections?<a name="line.132"></a>
<span class="sourceLineNo">133</span>   *<a name="line.133"></a>
<span class="sourceLineNo">134</span>   * @param c the collection for which to return an array of elements<a name="line.134"></a>
<span class="sourceLineNo">135</span>   * @param array the array in which to place the collection elements<a name="line.135"></a>
<span class="sourceLineNo">136</span>   * @throws ArrayStoreException if the runtime type of the specified array is<a name="line.136"></a>
<span class="sourceLineNo">137</span>   *     not a supertype of the runtime type of every element in the specified<a name="line.137"></a>
<span class="sourceLineNo">138</span>   *     collection<a name="line.138"></a>
<span class="sourceLineNo">139</span>   */<a name="line.139"></a>
<span class="sourceLineNo">140</span>  static &lt;T&gt; T[] toArrayImpl(Collection&lt;?&gt; c, T[] array) {<a name="line.140"></a>
<span class="sourceLineNo">141</span>    int size = c.size();<a name="line.141"></a>
<span class="sourceLineNo">142</span>    if (array.length &lt; size) {<a name="line.142"></a>
<span class="sourceLineNo">143</span>      array = newArray(array, size);<a name="line.143"></a>
<span class="sourceLineNo">144</span>    }<a name="line.144"></a>
<span class="sourceLineNo">145</span>    fillArray(c, array);<a name="line.145"></a>
<span class="sourceLineNo">146</span>    if (array.length &gt; size) {<a name="line.146"></a>
<span class="sourceLineNo">147</span>      array[size] = null;<a name="line.147"></a>
<span class="sourceLineNo">148</span>    }<a name="line.148"></a>
<span class="sourceLineNo">149</span>    return array;<a name="line.149"></a>
<span class="sourceLineNo">150</span>  }<a name="line.150"></a>
<span class="sourceLineNo">151</span><a name="line.151"></a>
<span class="sourceLineNo">152</span>  /**<a name="line.152"></a>
<span class="sourceLineNo">153</span>   * Returns an array containing all of the elements in the specified<a name="line.153"></a>
<span class="sourceLineNo">154</span>   * collection. This method returns the elements in the order they are returned<a name="line.154"></a>
<span class="sourceLineNo">155</span>   * by the collection's iterator. The returned array is "safe" in that no<a name="line.155"></a>
<span class="sourceLineNo">156</span>   * references to it are maintained by the collection. The caller is thus free<a name="line.156"></a>
<span class="sourceLineNo">157</span>   * to modify the returned array.<a name="line.157"></a>
<span class="sourceLineNo">158</span>   *<a name="line.158"></a>
<span class="sourceLineNo">159</span>   * &lt;p&gt;This method assumes that the collection size doesn't change while the<a name="line.159"></a>
<span class="sourceLineNo">160</span>   * method is running.<a name="line.160"></a>
<span class="sourceLineNo">161</span>   *<a name="line.161"></a>
<span class="sourceLineNo">162</span>   * &lt;p&gt;TODO(kevinb): support concurrently modified collections?<a name="line.162"></a>
<span class="sourceLineNo">163</span>   *<a name="line.163"></a>
<span class="sourceLineNo">164</span>   * @param c the collection for which to return an array of elements<a name="line.164"></a>
<span class="sourceLineNo">165</span>   */<a name="line.165"></a>
<span class="sourceLineNo">166</span>  static Object[] toArrayImpl(Collection&lt;?&gt; c) {<a name="line.166"></a>
<span class="sourceLineNo">167</span>    return fillArray(c, new Object[c.size()]);<a name="line.167"></a>
<span class="sourceLineNo">168</span>  }<a name="line.168"></a>
<span class="sourceLineNo">169</span><a name="line.169"></a>
<span class="sourceLineNo">170</span>  private static Object[] fillArray(Iterable&lt;?&gt; elements, Object[] array) {<a name="line.170"></a>
<span class="sourceLineNo">171</span>    int i = 0;<a name="line.171"></a>
<span class="sourceLineNo">172</span>    for (Object element : elements) {<a name="line.172"></a>
<span class="sourceLineNo">173</span>      array[i++] = element;<a name="line.173"></a>
<span class="sourceLineNo">174</span>    }<a name="line.174"></a>
<span class="sourceLineNo">175</span>    return array;<a name="line.175"></a>
<span class="sourceLineNo">176</span>  }<a name="line.176"></a>
<span class="sourceLineNo">177</span><a name="line.177"></a>
<span class="sourceLineNo">178</span>  /**<a name="line.178"></a>
<span class="sourceLineNo">179</span>   * Swaps {@code array[i]} with {@code array[j]}.<a name="line.179"></a>
<span class="sourceLineNo">180</span>   */<a name="line.180"></a>
<span class="sourceLineNo">181</span>  static void swap(Object[] array, int i, int j) {<a name="line.181"></a>
<span class="sourceLineNo">182</span>    Object temp = array[i];<a name="line.182"></a>
<span class="sourceLineNo">183</span>    array[i] = array[j];<a name="line.183"></a>
<span class="sourceLineNo">184</span>    array[j] = temp;<a name="line.184"></a>
<span class="sourceLineNo">185</span>  }<a name="line.185"></a>
<span class="sourceLineNo">186</span><a name="line.186"></a>
<span class="sourceLineNo">187</span>  // We do this instead of Preconditions.checkNotNull to save boxing and array<a name="line.187"></a>
<span class="sourceLineNo">188</span>  // creation cost.<a name="line.188"></a>
<span class="sourceLineNo">189</span>  static Object checkElementNotNull(Object element, int index) {<a name="line.189"></a>
<span class="sourceLineNo">190</span>    if (element == null) {<a name="line.190"></a>
<span class="sourceLineNo">191</span>      throw new NullPointerException("at index " + index);<a name="line.191"></a>
<span class="sourceLineNo">192</span>    }<a name="line.192"></a>
<span class="sourceLineNo">193</span>    return element;<a name="line.193"></a>
<span class="sourceLineNo">194</span>  }<a name="line.194"></a>
<span class="sourceLineNo">195</span>}<a name="line.195"></a>




























































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